the menard pressuremeter : history, equipment, new ... · prandtl 1920 developed an equation based...

www.apageo.com Ménard pressuremeter

Introduction for pressuremeter users

THE MENARD PRESSUREMETER : history, equipment, new developments, installation

procedures, design rules and methods

By Serge Varaksin, Vice Chairman TC211

Scientific Advisor

Guimarães, Coimbra October 16th and 17th 2015



2.1 History

2.2 Concept of pressuremeter

2.3 New developments

2.4 Installation procedures

2.4 Design rules and methods

2.5 Prestigious applications

2.6 ARSCOP project



Louis MENARD (1933-1978)

ENGINEER, INNOVATOR



SOME HISTORY

• First pressuremeter idea: 1933 : first expansion test of cylindrical probe 1955 : patent by Louis Ménard and first instrument to mesure « pressure-time » and « pressure-deformation » in cylindrical borehole Germany

(not pursued)

Ménard



KEY DATES OF ORIGINS

1955

Patent

1956

Master degree of L. Ménard

Louis Ménard, civil engineer and inventor of the pressuremeter

1958

First Company Michel Gambin (Mike) joins



PRESSUREMETERS IMPROVEMENTS WITHIN THE FIRST DECADE

D-9000 Versatile drill

G-type and GC-type

Pressuremeter

1971-1975 1955 1967

The second PMT prototype

1975

Soil-soils edited by Mike Gambin



WHY PRESSUREMETER?

• Performed in previously drilled hole to any depth • Performed in submerged sand or gravel, directly driven slotted

casing or STAF® method • Performed in fills even landfills (only possible technique) • Provides its own reaction • Large volume tested up to several tens of tons • Average soil response • Two stress-strain parameters • Creep information • Automatic data recording and test perfomance available • Pressuremeter modulus ( EM) (independent from porepressure) • Limit pressure (PLM), close to failure of plate, footing or pile tip



WHY STRESS CONTROLLED TESTS ?

• Strain is only consequence of stress and not its action

• Creep is available • In construction, loading is stress controlled



General principle of the pressuremeter

Cylindrical drilled hole

Objective : measurement of radial expansion of the drilled hole by application of a cylindrical stress through an expandable cylindrical probe

1- Operating system 1.a probe pressurising system 1.b measuring system of pressure and strain 2- Connections by coaxial flexible tubing 2.a probe pressurising system 2.b measuring system of pressure and strain

3- Cylindrical expandable probe 3.a pressure = stress applied on the soil 3.b deformation ( ε)



General scheme of a Ménard pressuremeter



Evolution of the pressuremeter



Detail of Ménard pressuremeter probe

Type G probe : Central Cell + Flexible Cover to form 2 Guard Cells. Central Cell Pressure is higher than in Guard Cells to balance cell membrane resistance. Pressure lag between the Central Cell and the Guard Cells is kept constant at a given Depth



Latest state of the art

• GeoPAC® + GeoBOX ⇒ High precision and high pressure

measuring tool.

⇒ Automatic piloting of the test, automatic recording and log presentation transmitted from GeoPAC® to GeoBOX® by Wifi and to the office by GPRS

⇒ Stress-controlled test (possibilities of cyclic program)

⇒ Ranges 0,1 cc to 100 Mpa



Evolution of drilling

• Drilling methods from European norm

- Hand auger - Power auger - Rotary drilling bit with bentonite injection - Shelby tube sampler - Slotted casing driving method - Roto percussion - Open slotted casing - Recent STAF® Method (Self bored tube system) - Self-boring pressuremeter probe under development



Guidelines for pressuremeter probe placement techniques



Slotted casing method

Cross section of a probe inside

a slotted casing



The Menard Pressuremeter : typical loading tests

Typical load tests conducted on foundations : (i) PBT; and (ii) PMT (not CPT or SPT)

PBT – vertical load test

PMT – shear loading test



Self bored tube system STAF®



STAF® technique : Ménard Pressuremeter Tests inside a self-bored slotted tube



Self bored tube system STAF®



Roto percussion drilling to reduce casing friction



Research pressuremeter: PAF and K0 meter



The pressuremeter curve

• Typical PMT field record (manual recording)



Typical PMT test

• Geobox automatic test piloting and recording



Typical PMT test report and interpretation



The expansion cylindrical cavity is an elastic medium according to Lamé :

Various moduli deformation linear elastic case

Young’s modulus (not applicable in soils!) Shear modulus Angular definition proportional to tangential stress

Shear anguler deformation under shear

Traction/compression /d=ε

εσ . E = γτ .G =

VP . V G

∆∆

=



What is a pressuremeter modulus

• Compression modulus • Shear modulus • Poisson coefficient (ν) • The relation between moduli is

• Ménard proposes to always adopt ν=1/3 so

εσ E =

G γτ =

-

=

d dφ

ν φ

G )2(1 E •+= ν

VP V )2(1 E mM ∆

∆+= ••ν

VP . )

2V V (V .

38 E 21

SM ∆∆+

+=or



Bearing capacity

• Prandtl and Terzaghi theory and limitations



Prandtl’s Theory on Bearing Capacity Analysis

Prandtl 1920 developed an equation based on his study of penetration of long hard metal puncher into softer materials for computing the ultimate bearing capacity. He made the following assumptions for the derivation. • The material is softer, homogeneous and isotropic. • The material is weightless and possesses only friction and

cohesion. • The problem is two dimensional • The base of the puncher is smooth. • The material behaves as a rigid body. • The volume change will be Zero. • The resulting deformation will be a plastic deformation.



Bearing capacity after Ménard Function of qL - qo = kp (pLM – po)

qL - qo = kp (pLM – po)

here qL is the ultimate bearing stress at the footing or pile tip - qo the vertical overburden stress at pile tip depth - kp the Ménard Bearing Factor at footing or pile tip and type of soil - pLM the Ménard limit pressure at footing or pile tip depth - po the insitu horizontal effective stress at footing or pile tip depth and it appears that, below a “critical depth”, the tip bearing capacity alone is much less than predicted by the c’ and Ф’ (Mohr - Coulomb)

Bearing capacity after Terzaghi Function of (h, γ, D, c, Ф)



Pressuremeter bearing capacity factor

Pressuremeter probe, equal active zone Surrounding soil passive reaction



Bearing capacity

• Piles and drilling shafts

The soil response in a pressuremeter test behaves much closer to the way soil reacts to a loaded deep foundation a fact observed by many researchers. It is the estimate of the settlement, which provides the value of the bearing stress in service (Terzaghi & Peck, 1948), especially in sands, when deeper foundations are considered. The soil around the tip is in a plastic state and the soil reaction around this sheared volume can be compared with the response to the expansion of a deeply embedded cavity. Elastic/plastic theory must be used.

Shallow foundation bearing failure against pile tip bearing failure in an homogeneous soil (EM & pLM constant).



Why Ey young modulus

F

σz σz

σz/2

σz/4

σz/8

σz

Ez/0

Ez/4

Ez/2

E

Duncan and Cheng

- Ez = variable not applicable for soils - Be careful with FEM - Stress distribution FEM is OK - Deformation analysis FEM not correct



Settlement and deformation

SF

E1

hΔh

cs

=

A/ Simple compression

where Ecs is the compression

F

h

(S)

∆hF

h

(S)

∆hr

0(F/S)

n

r

0(F/S)

n

P

PP

PP

∆rr

P

PP

PP

∆rr

P- P n

r

P- P n

rB/ Simple shear

where ν is the Poisson’s coefficient

C/ Simple compression P

P

P

P

P

P

P

P

r

P n

r

P nwhere E+ is the hydrostatic compression modulus



Settlement and deformation

D/ Menard deformation approach

Shear domain Spherical domain or volumetric

W(10 years)=



NO TENSION IN SOIL IMPACTS THE PMT MODULUS BECAUSE ELASTICITY ASSUMES TENSION

ORTHOTROPIC ELASTICITY

Briaud, Ménard lecture 2013



NO TENSION IN SOIL IMPACTS THE PMT MODULUS BECAUSE ELASTICITY ASSUMES TENSION

Briaud, Ménard lecture 2013



The Menard Pressuremeter : Settlement calculation under a footing

Valeur des coefficients de forme

0,00

0,50

1,00

1,50

2,00

2,50

3,00

0 2 4 6 8 10 12 14 16 18 20

valeur de L/2R

Coe

ffic

ient

s de

form

e

Lambda-s

Lambda-d



Type of material

Peat Clay Alluvium Sand Sand and gravel

E/pL α E/pL α E/pL α E/pL α E/pL α

Over consolidated >16 1 >14 2/3 >12 ½ >10 1/3

Normaly consolidated 1 9 -

16 2/3 8 - 14 ½ 7 -12 1/3 6-10 1/4

Weather or altered 7 - 9 1/2 1/2 1/3 1/4

E = the pressuremeter modulus of the soil, assumed to be homogeneous

P = the mean contact stress added to soil by the rigid footing

RO = a reference equal to 30 cm

α = The structure coefficient variable according to the nature of the soil and the ratio E/pL obtained from the pressuremeter, derived from the following table

Ménard Rheological coefficient α



Pile settlement prediction load transfer method

For the pile tip, the shear stress effect controls the settlement ΔR/R = [1/4G] Δp (6) Thus, the settlement zp of a pile tip is simply given (Frank & Zhao 1982) by : zp = ( B/λp ) qp (7) where B is the diameter of the pile - qp the pile tip pressure, with qp < qL, (Fig.2) and - λp is a factor which varies from 4.8 EM in coarse soils up to 11 EM in fine soils up to a stress of qL /2 and is 5 times smaller above the qL / 2 stress.

Load transfer method to estimate pile settlement (Frank & Zhao, 1982).

follows : zsi = ( B/λs ) qsi (8) where B is the diameter of the pile, qsi the estimated shaft friction of the ith element against the soil but limited by to a maximum of qs as shown in Fig.2 – values are given in Bustamante et al. (2009) and - λs a factor which - varies from 0.8 EM in coarse soils to 2 EM in fine soils up to a stress of qs /2 - and is 5 times smaller above the qs / 2 stress.



Description and Characteristics of 418 loaded and analyzed piles



Values for the tip bearing factor Kp



Selecting the Qi line to obtain the limit unit skin friction values qs



Direct Design using PMT Data. Chart for unit skin friction qs



GeoVISION® is a software that enables to extract, process and format of all data coming from APAGEO data loggers. Data is inserted through a USB device, memory stick, GPRS (option) or manual input. You can easily integrate notes, image or representative values of soil investigation.

Software for geotechnical data



SETTLEMENT UNDER HIGH RISE BUILDINGS IN CHICAGO

Measured 24 mm

TERZAGHI LECTURE 2009 Clyde N. BAKER Jr



Location Dead & live

Load DL + LL

Est. Settlement DL + 0,5LL

Measured Settlement

Elastic Theory Core Mat on 34 Caissons 602,110 kN 1,9 cm 1,2 cm

Isolated Caisson 66,725 1,2 to 1,9 cm 2,2 cm

Ménard’s Method Core Mat on 34 caissons 602,110 1,2 cm 1,2 cm

Isolated Caisson 52,490 1,9 to 2,5 cm 1,6 cm

NW Column on 3 Caissons 49,420 1,9 to 2,5 cm 1,6 cm

N Column on 3 Caissons 66,590 1,9 to 2,5 cm 2,0 cm

SETTLEMENT UNDER HIGH RISE BUILDINGS IN CHICAGO

TERZAGHI LECTURE 2009 Clyde N. BAKER Jr



CONCLUSION OF SETTLEMENT '94

• Soil non homogeneity disappears when using PMTs

• The ratio Settlement w / foundation width B remains constant

• Settlement curves are superposed when w/B is reported to measured pLM

• Settlement curves w = f(q) can be predicted from PMTs results

• The Louis Ménard’s bearing factor can be exactly derived from a simple analysis of the parameters of the loading test

• There is no size effect apparent in the settlement value of a square footing loaded up to the maximum safe load

• Then, the Terzaghi bearing capacity becomes questionable

ASCE GSP No.41 Vol.2 (1994) after J.L BRIAUD



Pressuremeter or traditional soil mechanics???

PRESSUREMETER RULES TRADITIONNAL SOIL MECHANICS

BEARING CAPACITY Parameters : PL; P0; he Test : pressuremeter all soils Theory : direct analysis ( precise)

Parameters C, Ф, D, h, γ Test : triaxal if clay Only correlation if sand Theory : Prandtl, Therzaghi (approximate)

SETTLEMENT Parameters EP; α; R(f(α)) Test : Pressuremeter, all soils

Theory : - Deviatoric precise - Volumetric f(α)

Parameters Cc; e0; Boussinesq Test : oedometer, triaxal if clay, only correlation if sand Theory : - Therzaghi oedometer (approximate) - Correlation Schmertmann (approximate)



PRESSUREMETER THROUGH INTERNATIONAL SYMPOSIUMS AND NORMS

1982 Paris, FRANCE

23 papers

1986 Texas, USA

26 papers

1990 Cambridge, UK

36 papers

1995 Sherbrooke,

CANADA

54 papers

2005 Paris, FRANCE

72 papers

USA => ASTM D 4719 Europe => EN ISO 22476-4, DIN EN ISO 22476-4 Russia => GOST 20276-2012

Applicable standards:



HyperPAC® and Rock mechanics

Simple, sturdy instrument



The probe

Schéma de la sonde 46mm THP

Total dimensions : 1100 * 380 * 340mm Weight : 40kg Maximal work pressure : 25 or 50 MPa Precision : pressure < 0,1 MPa volume < 0.05 cm3



Classification of soils and rocks based on pressuremeter parameters



SOIL AND ROCK CLASSIFICATION IN A EM/P0, P*LM/P0 DIAGRAM TO ASSIST FINDING THE RHEOLOGICAL FACTOR α

1

2

5

10

20

30

4050

100

200

300

400500

1000

4

5

10

15

202530405075100

0° 10° 20° 30° 40° 45°

0.1

0.5

1

5

10

50

100

500

12

3

4

5

6

6

7

78

8

1.0

10.0

100.0

1 000.0

10 000.0

100 000.0

1 000 000.0

α

Relative Ménard modulus EM /p0

x-axis alpha / granularity index

y-axis : relative modulus EM/po

oblique axis : relative limit pressure p*LM/po

EM/pLM

EM/pLM continued

Soil and rock classes limits

different rock examples [Baud & Gambin, 2011]

muddy

soft

firm

stiff (compact)

rocky

5)

1)

2)

7) 4)

6) 3)

8)

9)

Soil and rock classification in a EM/po , p*LM/podiagram to help finding α rheological factor

10)

12) hard rock

self bearingcapacity

Granularity index g 0 to 1 (Clay index a = 1- g)

MAIN SOIL AND ROCK CLASSES :1) Soft clay2) Firm clay3) Stiff clay and marl4) 5) 6) Mixed soil7) Loose sand8) Medium dense sand9) Dense sand and gravel10) Gravel and weathered rocks11)Soft rock12) Hard rock

1 : Weathered granite, Bologne, Italia2 : Liassic marls, Burgundy3 : Weathered gneiss, Limoges 4 : Fontainebleau stampian sandstone, Saulx-les-Chartreux (91, France)5 : Beauce oligocene limestone, Roncevaux quarry (45, France)6 : Sandstone & mudstone, Bacacak unit, Turkey [Tezel & al. 2013]7 : Urgonian limestone, Orgon (13, France) Eurogeo-Botte Fondation, unpublished]8 : Ordovician sandstone, Luxembourg, Eurasol, unpublished

11) soft rock



ARSCOP

A French national project to promote and foster geotechnical engineering based on pressuremeter

3 main objectives

•Consolidate and reinforce the French practice

•Continue with the development of the pressuremeter and its calculation methods

•Foster the pressuremeter outside France

FRENCH NATIONAL PROJECT ARSCOP



Task 1: Develop testing devices and test procedures to increase reliability and performance of the test

Task 2: Develop calculation methods and calculation models from the use of pressuremeter by incorporating the latest advances made in the field of

numercial modeling of geotechnical structures

Task 3: Creation of database for calibration and validation of calculation methods using results obtained from pressuremeter tests

+

Communication and Dissemination

(research reports, articles, guidelines, recommandations, standards, etc.)

WORK PACKAGES



FOUNDATIONS DESIGNED WITH MÉNARD PRESSUREMETER



OBRIGADO MERCI

THANK YOU

the menard pressuremeter : history, equipment, new ... · prandtl 1920 developed an equation based...

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